Derivative Financial Instruments - Schedule of Fair Value of Instruments with Credit-Risk-Contingent Features (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross liability fair value of contracts containing credit-risk-contingent features	$ 3	$ 10
Gross asset fair value of contracts containing credit-risk-contingent features and subject to MNAs	(2)	(3)
Collateral posted under MNAs for contracts containing credit-risk-contingent features	(1)	(5)
Maximum amount of additional exposure for contracts with credit-risk-contingent features if all features were triggered concurrently	$ 0	$ 2

Fair value of derivative asset, presented on a gross basis containing credit risk contingent features and which is subject to master netting arrangements.

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of derivative liabilities, presented on a gross basis containing credit risk contingent features.

+ References

No definition available.

+ Details

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Namespace Prefix:	all_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4H

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4H

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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